By my estimate, in about 5,000 generations - 125,000 years - male fertility will be roughly 1 percent of what it is now. Mutations in Y chromosomes are already known to reduce male fertility. So I see a slow decline in men's fertility until, eventually, men can no longer breed naturally.

Silver lining? 125,000 years may be enough time for lots of easy boy-doesn't-meet-girl jokes to be made.